针对Q690D高强度焊接结构钢焊接时容易产生焊接冷裂纹的问题,以50 mm Q690D高强度淬火回火钢的焊接实例为研究对象,分析了产生冷裂纹的原因,提出了防止冷裂纹产生的措施,并从焊材选用、焊接过程控制、焊接热处理等方面详细总结了该钢种...针对Q690D高强度焊接结构钢焊接时容易产生焊接冷裂纹的问题,以50 mm Q690D高强度淬火回火钢的焊接实例为研究对象,分析了产生冷裂纹的原因,提出了防止冷裂纹产生的措施,并从焊材选用、焊接过程控制、焊接热处理等方面详细总结了该钢种的焊接工艺要求及焊接要点。展开更多
Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999.Based on systematic analysis on the observational characteristics of these events a two-parameter(the rising time and ...Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999.Based on systematic analysis on the observational characteristics of these events a two-parameter(the rising time and the flux ratio of electrons to protons in each event)classification method was proposed to classify these events.The three clas-sified classes are(1)impulsive electron events with the flux ratio of electrons to protons being bigger than 1 and rising time being shorter than 200 min,(2)impulsive proton events with the flux ratio being smaller than 1 and rising time being shorter than 200 min,and(3)gradual proton events with the flux ratio being smaller than 1 and the rising time being longer than 200 min.In the past,"impulsive solar electron events"were under in-tense research.However,because the selection standards of their velocity dispersions or pitch-angle distributions were inadequate,statistical surveys of selected events were dif-ferent from each other and even some conclusions were not consistent with the theory,for example,the relation of type-III solar radio bursts to the"impulsive solar electron events".The first class of impulsive electron events are associated with type-III radio bursts and with clear velocity dispersions;therefore they ought to originate from the Sun.The second class of the events,which have short continuance time and usually are not associated with type-III radio bursts and without velocity dispersion,are still far away from inter-planetary shocks and most of them do not one-to-one correspond to corrotating interact-ing regions(CIRs);such events are possible results of local interplanetary magnetic field reconnection or electromagnetic disturbances.Finally,about 2/3 gradual proton events of the third class occur with interplanetary shocks,the delay times of which are almost equal to the rising time.Some of these events can be understood as particle accelerations by shocks.展开更多
基金the National Natural Science Foundation of China(Grant Nos.10425312,40574065 and 10333030)the Major State Basic Research Development Program of China(973 program)(Grant No.2006CB806302)the Chinese Academy of Sciences(Grant No.KJCX2-YW-T04)
文摘Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999.Based on systematic analysis on the observational characteristics of these events a two-parameter(the rising time and the flux ratio of electrons to protons in each event)classification method was proposed to classify these events.The three clas-sified classes are(1)impulsive electron events with the flux ratio of electrons to protons being bigger than 1 and rising time being shorter than 200 min,(2)impulsive proton events with the flux ratio being smaller than 1 and rising time being shorter than 200 min,and(3)gradual proton events with the flux ratio being smaller than 1 and the rising time being longer than 200 min.In the past,"impulsive solar electron events"were under in-tense research.However,because the selection standards of their velocity dispersions or pitch-angle distributions were inadequate,statistical surveys of selected events were dif-ferent from each other and even some conclusions were not consistent with the theory,for example,the relation of type-III solar radio bursts to the"impulsive solar electron events".The first class of impulsive electron events are associated with type-III radio bursts and with clear velocity dispersions;therefore they ought to originate from the Sun.The second class of the events,which have short continuance time and usually are not associated with type-III radio bursts and without velocity dispersion,are still far away from inter-planetary shocks and most of them do not one-to-one correspond to corrotating interact-ing regions(CIRs);such events are possible results of local interplanetary magnetic field reconnection or electromagnetic disturbances.Finally,about 2/3 gradual proton events of the third class occur with interplanetary shocks,the delay times of which are almost equal to the rising time.Some of these events can be understood as particle accelerations by shocks.
